Pressure testing of pipe



Aug. 21, 1951 w. H. WOODLIEF PRESSURE TESTING OF PIPE 4 Sheets-Sheet 1Filed Dec. 15, 1947 MU; I

- INVENTOR MLL/AM H WOUDL/EF ATTORNEY Aug. 21, 1951 w. H. WOODLIEFPRESSURE TESTING OF PIPE 4 Sheets-Sheet 2 Filed Dec. 15, 1947 IN V ENTOR W/LL/AM h: WOODL/EF A TTUENEY' W. H. WOODLIEF PRESSURE TESTING OFPIPE Aug. 21, 1951 4 Sheets-Sheet 3 Filed Dec. 15, 1947 INVENTOR WILL/AMH. WOUDL/EF.

ATTUHZVEY Aug. 21, 1951 w. H. WOODLIEF PRESSURE TESTING OF PIPE 4Sheets-Sheet 4 Filed Dec. 15, 1947 IN V EN TOR W/LL/AM H. WUUDL/EFATTUHAZEZY Patented Aug. 21, 1951 PRESSURE TESTING OF PIPE William H.Woodlief, Cleveland Heights, Ohio, as-

signor to Republic Steel Corporation, Cleveland, Ohio, a corporation ofNew Jersey Application December 15, 1947, Serial No. 791,749

9 Claims.

This invention relates to the pressure testing pipe and moreparticularly to such testing by static fluid pressure exerted internallyand in a manner preferably designed to keep the pipe under tension, dueto the pressure, rather than under any appreciable load of compression.

By way of example, it may be explained that pipe used in the oilindustry, particularly for well casing, is apt to be employed underextraordinarily severe conditions, particularly of tension on the pipeand on its threaded connections. Oil wells are lined with casings asthey are being drilled and as the hole is drilled deeper, section aftersect-ion of pipe is added to the string that forms the casing, and theweight of the entire string of pipe is at all times supported by thelast or top section. In consequence an enormous tensional load may beapplied to all of the pipe sections and their couplings, and it isextremely desirable that these parts he tested in advance for theirability to stand such a load.

One prior arrangement for testing oil well casing has involved pressinga water seal against opposite ends of a pipe section, and supplyingfluid under high pressure to the interior of the sealed section. In suchoperation, however, as the testing pressure increases the end thrust orpressure of the seals is also increased to compensate for the greaterfluid pressure, and the test is thus accompanied by considerablecompressive force or load, contrary to the conditions of actual use.Schemes have also been proposed with the view of avoiding compressionalload during the testing operation; one example of such arrangementsinvolves a pressure seal exerted on an auxiliary coupling member ofspecial shape at one end of the pipe and a spring-mounted, rotatableplug intended to be engaged with the other end of the pipe. However,this and other apparatus for such testing have involved a complexity ofequipment, or difiiculty of adjustment, or other operational.shortcomings or expense, and the present invention is .accordinglydesigned to ailord simple, eflective and entirely feasible procedure forrapidly testing lengths of'pipe in the course of manufacture.

Further and important objects of the invention are to provide convenientand rugged apparatus for testing pipe in the manner described, andespecially to provide such machine capable of accommodating relativelyheavy long lengths and yet adapted to avoid any compressive load on thepipe during the testing operation. Another object is to afford meanswhich will readily handle successive pipe sections, whether they are ofthe same or widely differing lengths, with an economy of time andeilort. and yet which will permit the interior of each to be subjectedto an extraordinarily high static pressure. Further objects are toprovide improved means for introducing the fluid under pressure to thepipe while the ends of the latter are sealed, and especially forintroducing fluid and then promptly increasing the fluid pressure to arelatively very large value. Additional objects are to provide animproved and more convenient apparatus for handling and moving the pipein the course of the testing operation, and to provide a simple andeasily op-, erated closure arrangement for sealing the pipe.

To these and other ends, including such as are hereinafter apparent orincidental to the use of the present improvements, one example ofapparatus embodying them is disclosed in the annexed drawings and thefollowing description, to which reference may be had, by way ofillustration, for an understanding of the several features andprinciples of the invention.

Referring to the drawings:

Fig. 1 is a plan view of pipe testing apparatus constructed inaccordance with the invention;

Fig. 2 is a side elevation of the apparatus of Fig. 1;

Fig. 3 is an enlarged end elevation, line 3-3 of Fig. 2;

Fig. 4 is a greatly enlarged vertical section on line 4-4 of Fig. 1;

Fig. 5 is an enlarged view, chiefly in vertical section on the centerline of Fig. 1, of the stationary pipe closure or tester head;

Fig. 6 is essentially an end view of the tester head as if seen on line66 of Fig. 5;

Fig, 7 is an enlarged view, chiefly in vertical section on the centerline of Fig; 1. of the spinning head near the left-hand end of Fig. 1;and

Fig. 8 is a transverse view partly in elevation and partly in verticalsection on line 8-8 (Fig. 7) of the chuck device shown at the left-handside of Fig. 7.

It may be explained that the specific apparatus here shown is designedto accommodate relatively long pieces or sections of pipe, e. g. 30 feetor more in length, such as are preferred for well casing and similarpurposes, and although machines embodying the disclosed principles maybe built to handle pipe of considerably difl'erent length or diameter,an outstanding feature of the invention is its peculiar adaptability forthe testing of long, heavy pipe sections as just mentioned.

Referring first to Figs. 1 and 2, the apparatus includes a closuredevice or testing head generally designated iii, a movable spinning headl2 for gripping and turning the pipe, and a long table or supportingarrangement generally desighated it on which the pipe is deposited andby which it is advanced lengthwise to the spinning head i2, which inturn cooperates to secure the end of the pipe in the closure [0. For thedelivery of pipe sections to the handling table, a plurality oftransverse skid bars 16 are disposed in spaced, parallel relation toeach other along one side of the table, having a gradual slope as shownin Fig. 3 so that successive pipes may be rolled from the bars to thetable.

Journaled in suitable bearings upon and above an elongated frame or bedIS, a series of V rollers alternately designated l9 and constitute afunctioning part of the tablel Each of the rollers 19, 20 has anannularly grooved or V-shaped sur= face, as best seen in Fig. 3, so asto center and align a pipe section on thetable, the axes of the rollersbeing parallel to each other, at right angles to the pipe. The rollers28 are power driven by appropriate reversible motors 2i and thealternate rollers ID are idlers, it being understood that the totalnumber of such rollers and the relative proportion of idling and drivenelements among them may be varied to suit the circumstances of use,except that for handling long pipes a multiplicity of rollers, e. g. asshown, appears preferable.

The frame l8 also carries a plurality of sets of transversely spacedrollers 23, i. e. arranged in pairs at successive distances along thetable. Each pair of rollers 23 is suported by a pneumatic or hydrauliccylinder 25 whereby it can be raised or lowered relative to the frame1'8 and the rollers l9 and 20, suitable connections (not shown) beingprovided for simultaneous control of all the cylinders. As shown therollers 23 have their axes parallel with the pipe and are spacedsomewhat laterally of and below the pipe axis, so that when the piperests on the pairs of rollers they act, so as to speak, as rollerbearing supports for rotation of the pipe. For clarity of illustration acomplete length of pipe is not shown in Figs. 1 and 2, but the positionof a portion is indicated by dotted lines 21, and a sectional view of itis incorporated in Fig. 3.

Means are provided for adjusting the vertical position of the frame l8,for instance relative to the further instrumentalities described below(i. e. to center the pipe with the stationary closure or for pipe ofdifferent diameter) and also if necessary, to facilitate changing thesupport of the pipe from the rollers l9, 2|! to the rollers 23. Suchmeans comprise a plurality of elevating mechanisms spaced along thetable, each designated 28 and including a pair of upstanding journalbearings 30 as shown in Fig. 3, seated on the floor or preferably in asuitable recess 3| in the floor. The bearings 30, 30 carry stub shaftsof corresponding crank arms 32 and 32' which at their outer endspivotally support an upright structure 34 having a top web or plate 35upon which a corresponding part of the frame 48 is seated. The crankarms 32' have an upstanding lever arm 31 which at its upper end ispivotally connected to a long operating rod assembly 39 that extends theentire length of the frame l8 and is carried in bearings in the latterin such manner as to prevent its longitudinal displacement except uponrotation as now to be explained.

The rod 39 has a threaded end 40 engaged by a manually or mechanicallyoperable wheel 4| which is rotatably Supported by the frame in themanner of a lead screw, so that as the wheel is turned the rod isgradually displaced in an axial direction. In consequence the upper endsof the several arms 37 are moved lengthwise of the table, rocking thecrank arms 32 and 32 and swinging the upright structures 34 about theaxes of the bearings 30. Thus the adjustment of the wheel 4|simultaneously operates all of the elevating mechanisms, to shift theframe I8 vertically, up or down in accordance with the direction inwhich the wheel is turned. To accommodate the necessary verticaldisplacement of parts when the table 14 is raised or lowered, rod 39 maybe provided with suitable universal joints or other sliding joints (notshown), permitting free movement of the table without affecting the rodend 39.

For removal of pipes successively from the handling table acorresponding series of skid bars 43 are disposed on the other side fromthe bars l8 but in a generally similar manner. To cooperate with thebars 43 a series of lift arms 45 (Figs. 3 and 4) each shaped to hookunder the pipe, are spaced along the table, and are carried on a longcommon shaft 45 that is rotatably mounted in suitable supports 41, sothat when the shaft is rotated the arms are moved in unison from theposition shown in Figs. 3 and 4 to lift the pipe and roll it back ontothe exit bars 43. It will be noted that the lift arms 45 arenormally.disposed with their pipe lifting surfaces well below thelocation of the pipe on the rollers l9, 2E8 or the rollers 23. Foractuation when desired, the shaft 45 is cormected by linkage 41 (Fig. 1)to suitable reduction gearing generally designated 48 which is in turnoperated by a motor 49.

Beyond one end of the table, e. g. at the left as seen in Figs. 1 and 2,a suitable base 50 carries the closure or tester device "I, and alsosupports the spinning head i2 between the device It) and the table 14.The spinning head .12 is designed to be traversed by the pipe, as thelatter is advanced lengthwiseby the V rollers, and then to engage thepipe for delivering it to, and for screwing it in, the tester device l0.As shown more particularly in Figs. '7 and 8 the upper part of thespinning device comprises a tubular head element 52, axially alignedwith the pipe on the table and mounted for rotation about such axis, insuitable bearings 53, 54. Keyed to the tubular element 52, a gear 56 isprovided, which through further gearing generally designated 58,constitutes a driving connection to the element 52 from a source ofpower such as a reversible motor 60 (Fig. 1).

At one end the tube 52 carries means for gripping the pipe, i. e. byfrictional or like engagement with its exterior surface. In theapparatus shown, the gripping means comprises an annular series ofchucls generally designated 52, including pairs of overlapping chuckmembers 63, 64 alternatively engageable with the pipe for forward orreverse drive respectively, and having gripping projections 65, 66. Eachpair of chuck members is pivoted on a stud 68 and each member at itsouter end has a slot 69 receiving a rod or stud 10. Each stud 10 thusactuates both members of a pair so that the latter may rock togetherrelativeto'a radius of the stud 68, upon angular displacement betweenthe studs 63 and the studs I0 about the axis of the member 52. ,Thuswhen the members are swung in one direction, e. g. into the positionshown, the projections 65 are moved inward to and which is mounted forlimited angular movement relative to the plate II, each of the plates II, I2 being centrally apertured to clear the pipe. The base of thespinning head bearing structure has a traveling support 16 arranged formotion along a track 18 in a direction lengthwise of the pipe. Throughrack and pinion or other appropriate mechanism (not shown) in the housinof the support 15, the spinning head may thus be advanced toward orretracted from the closure device 10, e. g. by turning a hand orotherwise operated wheel 80. It may be explained here that each pipe 21fed to the receiving V rollers I9, is externally threaded at each endand carries, tightly screwed on its end 85 (Fig. 5) remote from thespinning head, a coupling sleeve 86. For the testing operation andpreferably before the deposit of the pipe on the V rollers, a plug 88 isfirmly screwed into the open end of the coupling 85, thus providing asimple but effectively sealed closure for the end 85, wholly movablewith the pipe.

Referrin now to Figs. 5 and 6 as well as Figs. 1 and 2, the closuredevice I0 for the other end comprises a body portion 90 fixed on thebase 50 and carrying a female coupling element 9| in alignment with thepipe as the latter is supported and advanced by the means hereinabovedescribed. The coupling 9|, thus stationarily secured, is internallythreaded to engage the external threads around the open end 92 of thepipe. The body portion 90 has a longitudinal passage 93 opening throughthe vertical face 93a communicating with the pipe to be tested. Througha check valve 94, the passage 93 communicates with a conduit 95 forsupply of water pipe. At this time the transversebearing rollers 23 maybe elevated by actuation of their hydraulic or pneumatic cylinders 25,to lift the pipe from the V rollers I 9 and 20.

The hand or otherwise operated wheel 80 is now turned, moving thespinning head and the pipe toward the closure device l0 until the end ofthe pipe abuts the coupling element 9|. Thereupon the motor 60 isenergized to rotate the head 52 and consequently the pipe-for example ina clockwise direction in Fig. 3-so as to screw the end of the pipe intothe coupling element 9|. Preferably, rotation of the pipe may commencebefore it actually abuts the coupling, but in any event propercoordination of control of the hand wheel and the motor 50 is easilyachieved to initiate the desired threaded engagement between the pipeand the coupling. Continued rotation of the spinning head thenautomatically screws the pipe into the coupling (without further use ofwheel 80), and finally, the rotation is interrupted when the pipe istightly secured. For best operative convenience in most cases, the motor60 can be of such type, or have such clutch connection, as may simplypermit the spinning head to be automatically stopped by the tighteningof the threaded engagement-all without damage under low pressure ashereinbelow explainedtqs Another conduit 91, of smaller diameter, opensinto the passage 93 for communication with a source of water under highpressure, e. g. as furnished by a suitable pump (not shown).

When the pipe is being filled with water the displaced air should beremoved, and for that purpose a supplemental passage 99 opens into theface 93a at its upper edge and extends to a manually or pneumaticallyactuated purge valve I00 from which the air can be discharged through anoutlet MI. The purge valve I00 may be of a type normally biased to aclosed, pressure-tight position.

With the described instrumentalities, the operation for testingsuccessive pipe lengths is easily performed and requires little or noskill on the part of the attendants. Pipes to be tested are placed onthe skid bars l5, and while there may be fitted with the couplings 85and the plugs 08 at their outer ends 05. With the V rollers l9 and 20 inreceiving position, one pipe is moved onto the rolls, where it comes torest as shown in Fig. 3. The motors for the rollers 20 are thenenergized, turning the latter and advancing the pipe lengthwise to andthrough the tubular portion 52 of the spinning head l2. The drive of therollers 20 is interrupted when the pipe end 92 extends a. short distancebeyond the cover plate 13, and the chucks 62 are then manually operated.hv the handle 12, to grip the to the motor or other driving parts.

Both ends ofthe pipe are now sealed and its end 92 is securely held bythe coupling element 9| of the closure device, the remainder of the pipesimply resting on the transverse rollers 23 which constituted a-rollersupport during the screwing-in operation. The plugged, remote end islongitudinally free and there is no compressive force on the pipethroughout its entire length. If desired, the chucks 62 can also bereleased at this time.

The check valve 94 is then opened to allow water to flow into and fillthe pipe through the passage 93, and as the interior fills, the purgevalve I00 is operated (for example, being airor oil-actuated) to releasethe entrapped air. The.

water thus supplied through the conduit 95 is under an approximately lowpressure, for example about 40 pounds per square inch, so that the pipecan be filled without entrapment of air bubbles or other adverse effectdue to turbulence. When the pipe is completely filled the check valve94, which may be an air operated device of known construction,automatically shuts off the low pressure inlet, thus sealing theleft-hand end of the passage 93 so that the subsequent application ofhigh pressure will not be impaired by causing thev water to back up inthe conduit 95. The purge valve I00 being also closed, pumping or otheroperation is then initiated to supply water under high pressure, or toraise the pressure in the system, through the line 91; if desired,energization of suitable pumping instrumentalities can be automaticallyeffected by the aforesaid actuation of the check valve 94, throughappropriate control devices, not shown. The high pressure pump continuesin operation, to build up to the required testing pressure in the sealedsystem including the pipe 21. For example, to test well casing that hasa 7 inch outside diameter, a pressure of about 2800 pounds per squareinch should ordinarily be reached. Finally, to complete the test, thepipe can be held at the stated or other selected maximum pressure for adesired period of time.

After the actual testing cycle is thus finished, the high pressure pumpis stopped and urge valve I00 is opened to relieve pressure in the pipe.

The chucks 62 are actuated to engage the pipe for reverse rotation andto eifectuate such rotation the motor 80 is energized in reverse orthrough suitably reversed driving mechanism. Accordingly the spinninghead I! unscrews the pipe from the stationary coupling element 9 I andwheel 88 can then be turned, to back the pipe away from the closuredevice. When the pipe is free of the latter the spinning head isstopped. the chucks 82 are released and the relative positions of thetransverse rollers 23 and the V rollers I8, 20 are restored to theiroriginal position so that the pipe again rests on the V rollers. Thedriven V rollers 20 areenergized in reverse, to move the pipe away fromthe spinning head and back along the table, it being understood thatduring this time, the water may run out of the open end 82 01' the pipe,to be caught by a suitable sump, not shown.

Finally when the pipe has reached an appropriate location on the tableII, the V roller drives are interrupted and the mechanism including themotor 49 is started, to rock the lift arms 45, clockwise as seen in Fig.3, so that they raise the pipe and roll it oil onto the exit skid bars43. There the plug 88 can be removed, leaving the coupling 86 in place;and if the pipe has withstood the test, it may be advanced to otherlocalities, e. g. for painting and shipping.

It will now be appreciated that the described instrumentalities affordeda thoroughly effective performance of the testing operation with fluidata desired high pressure. At the same time, there are no compressiveloads whatever on the pipe and full tension may be developed through- Iout its length, e. g. between the oppositely directed forces of pressureon the plug 88 and the closure body portion 90. respectively. Thus thethreads at each end of the pipe are under tension, as well as the pipeitself. This tension may be very considerable; for example, a 7 inchoutside diameter pipe having a 3 inch wall resulting in an insidediameter of 65 inches has an internal crosssectional area of about 35square inches, so that a total force of about 98,000 pounds is exertedat each end of the pipe, i. e. against the inner side of the plug 88 andagainst the closure body portion 90, when the water pressure has reacheda value of 2800 pounds per square inch.

The arrangement is extremely simple to use, requiring'no particularskill at any stage, and provision is made for properly supporting andguiding the pipe at all times, so as to avoid damaging or deranging itin any way. Although the apparatus is particularly eifective for ahydrostatic tes't, e. g. with water, it will now be seen that equipmentembodying the described principles may be adapted for use with otherfluids, either gaseous or liquid.

It is to be understood that the invention is not limited to the specificapparatus herein shown and described, but may be carried out in otherways without departurefrom its spirit as defined by the followingclaims.

I claim:

1. Pipe testing apparatus comprising, in combination, a stationaryclosure for one end of a pipe to be tested, said closure having threadsto engage threads at said end of the pipe and being thereby arranged tohold the pipe against longitudinal displacement, solely by said threadedengagement, and said closure including means for introducing fluid underpressure to the interior of the pipe, means releasably engageable withthe pipe for rotating the latter to screw its aforesaid threads intoengagement with the threads of the closure, said pipe-rotating meansbeing movable to carry the pipe longitudinally to and into threadedengagement with the closure, supporting means for the pipe arrangedcooperatively with the closure to support the pipe wholly free oflongitudinal compression relative to said threaded engagement with theclosure, and a removable closure for the other end of the pipe, movablewith the pipe to avoid longitudinal compression of the latter.

2. Pipe testin apparatus comprising, in combination, a non-rotatableclosure to which one end of a pipe is to be screwed, pipe supportingmeans to hold the pipe in alignment with said closure, meansintermediate said supporting means and said closure and engageable withthe pipe for rotating the latter to screw its end to the closure, saidclosure including means for introducing fluid under pressure to theinterior oi the pipe and said supporting means including means rotatableabout an axis transverse of the pipe for rolling the latter to the piperotating means, and a removable closure for the other end Oi the pipe,movable with the pipe to avoid longitudinal compression of the latter.

3. kipc testing apparatus comprising, in combination, a stationaryclosure adapted to be releasably secured to an end of the pipe uponrotation of said pipe relative to the closure, means for supporting thepipe in alignment with the closure, and means disposed adjacent theclosure device in alignment with the supporting means and releasablyengageable with the pipe, for rotating the latter in a manner to secureit to the closure, said pipe-rotating means being movable toward andaway from the closure to bring the end of the pipe into engagementtherewith for said securing operation by the pipe-rotating means, andsaid closure including a passage therethrough and having means connectedtherewith for supplying fluid under pressure to the interior of thepipe, and a removable closure for the other end of the pipe, movablewith the pipe to avoid longitudinal compression of the latter.

4. Pipe testing apparatus comprising, in combination, a non-rotatableclosure to which one end of a pipe is to be screwed, pipe supportingmeans to hold the pipe in alignment with said closure, meansintermediate said supporting means and said closure and engageable withthe pipe for rotating the latter to screw its end to the closure, saidclosure including means for introducing fluid pressure to the interiorof the pipe and said pipe supporting means including a set of V-roilerson axes transverse of the pipe, adapted to support the latter andadvance it to the rotating means, a set of transversely spaced rollersonaxes parallel to the pipe adapted to constitute roller bearing supportfor the pipe to facilitate rotation thereof, said first andsecondnientioned rollers being selectively disposable in pipe-supportingposition, and means for moving one set of rollers relative to the other,to shift the support of the pipe from one to the other. and a removableclosure for the other end of the pipe, movable with the pipe to avoidlongitue-inal compression of the latter.

- 5. Pipe testing apparatus comprising, in combination, a closure devicefor the end of a pipe, including a female member internally threaded toreceive external threads on said pipe end, and means for introducingfluid under pressure into the pipe thereby attached, a spinning devicethrough which the pipe can be longitudinally inserted and which includesrapidly releasable means to grip the pipe, for rotating the same, saidspinning device being movable to carry the pipe longitudinally intoabutment with ,said female member for rotative operation of the spinningdevice to screw the pipe into said member, and supporting means forthepipe aligned with the closure and spinning devices, including meansrotatable about an axis transverse of the pipe for rolling the latter tothe spinning device.

6. Pipe testing apparatus as described inclaim 5, wherein the fluidintroducing means comprises passage means to communicate with the pipefor supplying liquidat a low pressure to fill the pipe and thereafter ata higher pressure to produce longitudinal tension in the pipe, andcooperating passage means for removal of air from the pipe as it isfilled, and wherein the last mentioned rotatable means comprises aplurality of spaced V-rollers with their V grooves aligned to receivethe pipe, and said supporting means alsov including, on each side of thepipe and beneath the same, a plurality of rollers having axes parallelto the pipe and adapted to provide a roller bearing'for the rotation ofthe pipe by the spinning device, said last mentioned pluralities ofrollers being movable relative to the plurality of V-rollers so that thepipe may be engaged and supported selectively by either the V-rollers orthe last mentioned rollers.

7. Pipe testing apparatus comprising, in combination, a stationaryclosure for one end of a pipe to be tested, said closure having threadsto engage threads at said end of the pipe and being thereby arranged tohold the pipe against longitudinal displacement, solely by said threadedengagement, and said closure including means for introducing fluid underpressure to the interior of the pipe, means releasably engageable withthe pipe and adapted to be turned for rotating the pipe to screw itsaforesaid threads into engagement with the threads of the closure, saidpiperotating means being movable axially with the pipe as the threads oithe pipe are screwed into engagement with the closure, whereby said pipemay be held against longitudinal displacement only by said firstmentioned closure, and a removable closure for the other end of thepipe, movable III with the pipe to avoid longitudinal compression of thelatter.

8. Pipe testing apparatus comprising, in combination, supportingstructure for the pipe to be tested, including means selectivelyengageable with the pipe to advance the latter longitudinally or tosupport it for free rotation about its axis, a stationary closure devicedisposed in alignment with a pipe supported on said structure andadapted for releasably sealing an end of the pipe, said device includinga stationary threaded portion to be engaged by threads at the end of thepipe upon rotation of the pipe, means connected with said closure devicefor introducing fluid under pressure to the interior of the pipe throughthe closure device, means releasably adapted to grip the pipe uponadvancement of the latter thereto for rotating the pipe into engagementof its threads with said threaded portion, and a removable closure forthe other end of the pipe, freely movable with the pipe and supportedsole- 1y thereby.

9. Pipe-testing apparatus as described in claim 8, wherein thepipe-rotating means is disposed intermediatethe pipe-supporting meansand the closure device, and wherein the pipe-rotating means comprises arotatable head having an opening to be traversed by the pipe, chuckmeans on the head around the opening for gripping the pipe, and drivingmeans for rotating the head.

WILLIAM H. WOODLIEF.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 640,881 Deming Jan. 9, 19001,187,665 Simms June 20, 1916 2,122,760 Scott et a1 July 5, 19332,183,974 Richardson Dec. 19, 1939 2,231,807 Hybarger Feb. 11, 19412,242,658 Protin May '20, 1941 2,293,107 Branham Aug. 18, 1942Certificate of Correction Patent No. 2,565,460 August 21, 1951 WILLIAMH. WOODLIEF It is hereby certified that error appears in the printedspecification of the above numbered patent requiring correction asfollows:

Column 6, line 45, for approximately read appropfiately;

and that the said Letters Patent should be read as corrected above, sothat the same may conform to the record of the case in the PatentOflice.

Signed and sealed this 8th day of January, A. D. 1952.

THOMAS F. MURPHY, Assistant Uammz'ssioner of Patents.

